Workers fill baskets at a flood wall in Plaquemines Parish on Tuesday. The area is about 25 miles south of New Orleans. Photograph: Gerald Herbert/AP

Plaquemines Parish styles itself as a "Blue Ribbon Resilient Community" and its location demands a certain ingrained stubbornness from those who call it home.

It probably appears desolate and defensive even on a sunny day as state highway 23 winds along the Mississippi River through the small town of Belle Chasse with its tired strip malls, past the naval air base and the Chevron chemical plant with its sign that proudly declares: "No one gets hurt. Ever."

A 25-minute drive south-east of central New Orleans, Plaquemines is flat, low-lying and surrounded by water. There is only a sinuous sliver of habitable land. An array of bayous, ponds, bays and islets protrudes far out into the Gulf of Mexico, making it feel isolated and vulnerable.

The parish president, Billy Nungesser, says that after Katrina, the area was all but forgotten. "I ran for parish president because after Katrina, nobody came down to help us. It was all about New Orleans. And I made a commitment to rebuild this parish. Over $2bn of levee improvements, community centers, power stations – things are better than they've ever been in this parish," he said.

Nungasser spoke at the busy parish offices in a defiant-looking brick building raised above the ground by pillars – a bunker on stilts. A short drive down the road, the auditorium has become a shelter for the displaced.

About 7,000 Plaquemines residents out of the population of 23,000 were ordered to evacuate, and many of those who could not or would not skip town are holed up here in a well-preserved old hall with gold-painted chandeliers and ceiling fans. Folding beds are arranged in neat rows and seats face a flat-screen television and a kitchen. Naval officers and police look on.

"This building holds 80, next building 200, the backup location which we've overflowed to we have a capacity of 200. We're already pretty full. We're at 340," Gina Meyer, the superintendent of emergency medical services, said on Tuesday.

"Because of all the federal money that was spent on the federal protection system, Belle Chasse is protected. That allows us to keep those residents here. Historically we would have to bus them three to five hours away. A lot of elderly, sick, it'd be very difficult for them," Nungesser said.

He believes Isaac is far less menacing than Katrina. "It's no comparison in the damage it could cause. But two nights ago when I tried to go to sleep, I couldn't. And I got phone calls all night because this storm came off of Florida large, unpredictable as Katrina. People said: 'Billy, when I wake up tomorrow morning are we going to be facing another Katrina?' Honestly, I couldn't tell them know, I didn't know. Luckily the next morning the storm didn't strengthen, it didn't get its act together."

Still, he admitted that the new levees are not capable of fully repelling very high rises in the water level. "The two levees that we're concerned about, the east bank we have a brand new levee at eight feet and the storm surge projection was eleven feet, that wasn't good. The latest models show that that dropped to five to seven feet so that's good," he said on Tuesday.

"On the west bank we have a section of levee that's five feet and were projecting a storm surge of seven to nine feet. That has now dropped to about four to six feet, so that's a good thing."

Quinton Washington, a minister, took advantage of a brief break in the rain to stand outside on the shelter's porch next to a high school football field. "I have a bed with supplies, blankets and pillows so that's all I could ask for. The big difference between this parish and New Orleans is they give you a place to shelter. … That's a blessing in itself," he said.

Jaden Fabian, 1, and her family evacuate their Plaquemines home. Photograph: Gerald Herbert/AP

When Katrina struck, Washington lived in New Orleans, but his home was ruined and he was relocated here by federal authorities. "I rebuilt and restored my life," he said. But he lives only three miles from the coast: "I'm absolutely worried about our house."

The mandatory evacuation zone starts a couple of miles south of the shelter. Police cars and cones block the road. But "mandatory" appeared to be a subjective concept this afternoon, as the police allowed those who live at the southern tip to pass through and return home. Trucks erected flood barriers, just a few feet from single-storey homes.

One resident pushing south regardless, a 21-year-old named Joseph Buras, said he lives with his father and brother "as far as you can go, right at the end" of the road.

He was sanguine about the risks. "The worst it's probably going to get is 90mph winds, so people aren't in so much of a panic as they normally would. Then again the fear of Katrina is still in a lot of people's hearts. So when they heard a hurricane was coming they just hauled it," he said.

"We've survived the worst, this isn't the worst. We built our house almost like a fortress and it stood. Katrina didn't move the house at all – but the water damage and wind damage tore it to pieces. … After Katrina everything was gone. You could stand on the top of my car and look for miles because the trees were gone. It looked like a nuclear blast had gone off. "

He has little faith in the new flood defenses. "I'm very unimpressed. The levees down there don't look too good. Just a few months back I was on my bicycle on top of a levee and half of it gave way. It's just mud," he said. "It took them a year to fix a single pump. … They were stalling and stalling and stalling."

Buras said he would not feel safe in a shelter. "Last time I went to a shelter I almost had my throat slit in my sleep. In terrible times, people do terrible things. I had a bottle of water on me, he wanted it, so … People were flooding in and out, hundreds of people, [the authorities] weren't able to keep track."

Fearing looters, he thinks Isaac might be less of a problem than his neighbors. "It's the perfect time. You have people leaving and it was such a quick evacuation that not a lot of people were able to take everything they wanted with them. A lot of sick, sick people like to stay behind and take advantage," he said.

But Buras will not move, whatever the threat, because he refuses to let any hurricane rip up his roots. "It's where I was born, it's my home," he said. "The town where I live was named after my family. We founded that area. It's part of me. I couldn't live anywhere else."